I have the handheld and the "after" performace is noticeable and awesome!! He puts the same tune in the new ecm as he does in the handheld. With the handheld you are just "manually" uploading the tune versus swapping out and ecm. He did this because some of us didn't want to go to dealer for CASE relearn and also with this he includes the modified TCM tune. This also gives ability to put car back to stock tune.
Mark
Mark